The present invention relates to a process for making a molded game ball particularly for volley-ball, hand ball and soccer, with a network of rubber ribs between individual cover segments upon the surface of the molded game ball, the carcass of which is wrapping an inflated rubber bladder with a textile layer or in winding thereon strands of ropes, yarn, threads or filaments to form the so called bag.
Among the most important properties of game balls, which are being manufactured by the molding process, one may, from the viewpoint of their appearance, count the distinctly showing outline network of ribs from rubber, which are quite accurately limiting the fields of individual cover segments; these are mostly made of natural or synthetic leathers, adhesive bonded to the specifically adapted carcass of the inflated rubber bladder. This type of game balls has been increasingly asserting in the past years with athletic games; this on the other hand influences also the manufacture of the game balls owing to the fact, that the relatively simple manufacturing process has proved to be much cheaper than the manufacture of analogous game balls, made heretofore by the classical method of manually sewing the outer cover of the game balls from individual leather segments.
The utility properties of the molded game balls are mostly characterised as satisfying; however, it is more or less of prestige reasons that the manufacturers of the molded game balls are aiming towards the manufacture of molded game balls, which would to a maximum degree, not excluding even the overall appearance thereof, suggest the appearance of the classical, manually sewn game balls. This aim of the manufactures, or in other words, this prestige component, has, after all, an effecting influence even on the sportsmen themselves when, at the athletic games, they are using the molded game ball.
To form the aforementioned rubber ribs on the surface of the molded game balls, several manufacturing methods have been proposed so far. According to the manufacturing process disclosed in Czechoslovakian Pat. No. 135,824, to the game ball bag, that is to the inflated inner rubber bladder which has been coated with a textile coating, rubber bands of the ribs are adhesively bonded to selected positions, the final form and the distribution thereof are finally given by putting the bag into a mold and by heat pressing them therein, during which the rubber material of the ribs is vulcanised. Thus, the ribs formed are limiting the individual fields for adhesive bonding to the cover segments. A substantially analogous manufacturing process is to be assumed also from the study of the French Pat. No. 1,488,920, although here, the precise process for the manufacture of the rubber ribs has not been clearly disclosed. The U.S. Pat. No. 3,887,416 discloses the adhesive bonding of the ribs, made of rubber, which has been vulcanised in advance. Manufacturing processes are also known (U.S. Pat. Nos. 3,653,818 or 2,219,078), according to which rubber ribs are made, the height of which reaches over the height of the cover segments. As admitted even by the manufacturers of these game balls, the game balls provided with rubber ribs of this type have proved to be unsatisfying, because if the ribs extend little beyond the surface of the ball, they do not enable a reliable gripping of the game ball into the hands of the player on the one hand, while on the other hand, if they extend substantially beyond the surface of the ball, they negatively influence the bounce properties of game balls.
The mutual disadvantage of all of the described manufacturing processes may, above all, be seen in the comparatively complicated manufacturing procedure, which is this way becomes needlessly expensive, much to the detriment of the remaining manufacturing steps of the manufacture of the molded game balls.